Car windows will be defrosted by transparent films

5 September 2019 г. FRS KSC SB RAS

The unique conductive materials developed in Krasnoyarsk allow instantly defrosting automobile windows over the entire area, while maintaining their full transparency. New technologies will also be useful in construction and design - an innovative self-adhesive film can be applied to any glass in a house or an office, turning it into a safe and energy-efficient heater. Another area of their application is fast tinting of any glass surfaces. These films are obtained using a new method which is several times cheaper than lithography used in producing foreign analogues. Krasnoyarsk scientists gave an interview to the journalist of the newspaper Izvestia.

“Technology on the bank”

Technical ideas are often prompted by nature. So, on the bank of one of the Altai rivers, a senior research associate of the Krasnoyarsk Science Center SB RAS, Stanislav Khartov paid attention to a part of the landscape with an unusual structure: small fragments of soil were outlined by narrow grooves which formed when dried in the sun. This natural phenomenon became a prototype of a self-organizing template, which allowed creating an innovative conductive material with minimum cost.

The technology of its production is the following: a thin layer of biodegradable polymer capable of dissolving in water is applied to a plastic film. Then, the workpiece is put into a special chamber to be exposed to hot air up to 50 degrees. As a result, the surface layer is deformed, becoming covered with a network of cells bounded by deep cracks. Moreover, their size can be changed by varying the parameters of the biodegradable polymer and intensity of thermal exposure.

“We call the resulting template self-organizing, because we set only external conditions for it, and the template forms the cells of arbitrary shape independently, - says Stanislav Khartov - This method is several times cheaper than the lithography methods used abroad to create conductive films.”

“Dancing” template

Next, the workpiece is placed into another chamber, where a metal is sputtered onto it, filling all the cavities between the cells and depositing on their surface.

“At this stage, we use a fundamentally new solution to activate the template - each of its elements begins to move during the sputtering process, which prevents metal paths from being connected to the layers covering the cells,” says Stanislav Khartov.

This method of applying metal allows one to safely remove its excessive amount along with the template which is not needed anymore in the next stage of production. To do this, scientists use a water wash, after which intact conductive metal paths, two microns in thickness and five microns in width, remain on the film surface.

According to the developers, owing to the active template, they were able to four times increase the thickness of the metal layer as compared to the closest American counterpart created using an expensive lithographic template. At the end of the production process, the material is covered with a transparent layer of single-walled carbon nanotubes.

A big advantage of the new films is their low cost, since no expensive equipment is used in their production, in particular vacuum sprayers.

Full visibility

One of the main areas of application of the innovative films is the production of automobile windows with electric heating, which ensure comfortable operation of vehicles in the winter season.

“Now molybdenum filaments with a thickness of 30-50 microns are used for this purpose, which are clearly visible to the naked eye,” the researcher explains - When using our innovative films, the glass remains completely transparent. It also heats up faster when the system is turned on by reducing the dielectric gaps between the metal paths in the new material.

Slight dimming

The new technology can also be useful in the field of car tuning: we are talking about the production of films with the dimming function. As in the case of heating, this solution is also applicable for windows of residential and office premises.

To create such a product, a thin layer of electrochromic composition is applied between two conductive films. Unlike similar solutions requiring the replacement of old glasses, new films can be glued directly to them, which will make tinting more affordable for consumers. In addition, new films will function efficiently at subzero temperatures.

Currently, the developers have successfully completed the research stage, creating a number of working prototypes. At the same time, about 2 km of transparent conductive film has already been produced for experimental purposes, which made it possible to refine the production technology.